The present invention relates to a burglar alarm system mounted in a doorway framing, and more particuarly the secured doorway framing including a protective reinforcement steel plate preventing unlawful entry into a structure closed by a door, such as fully disclosed and claimed in my U.S. Pat. No. 4,074,484, dated Feb. 21, 1978, whose disclosure is incorporated herein by way of reference.
The doorway framing disclosed in my patent comprises a wooden door jamb having two substantially parallel major faces and two minor faces substantially perpendicular to the major faces. One of the major faces has a recessed end portion delimited by one of the minor faces and a shoulder constituting a stop for a door. The door jamb defines a door latch bolt hole in the recessed end portion. The door jamb is mounted on a wall including wooden stud means adjacent the other major face of the door jamb and the minor faces of the door jamb extend substantially parallel to the wall. A reinforcement metal plate extends over a substantial portion of the wall stud means and a substantial portion of the one minor face of the door jamb, and is securely affixed to the wall stud means and the one minor face of the door jamb, covering a substantial region of the minor door jamb face adjacent and beyond the door latch bolt hole. The securely affixed plate holds the door jamb firmly in position.
In my copending patent application Ser. No. 888,412, filed Mar. 20, 1978, I have disclosed an improvement in such a doorway framing, which comprises a rigid backer plate arranged in the narrow space between the other major face of the jamb and the wall, the backer plate being screwed to the other major face of the jamb whereby the door jamb is sandwiched between the striker and the backer plates and the striker plate is firmly anchored to the jamb. The disclosure of this application is incorporated hereby by way of reference.